A new Danish study found that the use of hormonal intrauterine devices (IUDs) is associated with a slightly higher risk of breast cancer in women aged 15 to 49. The research indicates that women using hormonal IUD contraceptives have a 40 percent higher chance of developing breast cancer compared to nonusers.
This increase sounds high, but breast cancer is still rare in younger women. For perspective, this 40 percent higher chance means about 14 extra cases of breast cancer per 10,000 women using hormonal IUDs, on top of the baseline risk for this age group.
“We are much more confident that this is an association that we should take seriously,” lead author Lina Steinrud Morch, who holds a doctorate in public health and is a team leader at the Danish Cancer Institute, told The Epoch Times.
“I think the take-home message would be that ... a hormone IUD is not only working locally in the reproductive system, it is also working systematically in the body,” Morch said. “And that’s very important information because a lot of women have been choosing that product because of the assumption that it would be working only locally.
IUD Use and Breast Cancer Risk
Published in the Journal of the American Medical Association on Oct. 16, the study identified the hazard ratio, which measures the differential risk of breast cancer between hormonal IUD users and nonusers over time.The researchers tracked a cohort of 157,190 women (half IUD users and half nonusers) aged 15 to 49 for up to 15 years, during which approximately 1 percent of women were diagnosed with breast cancer.
Researchers found that hormonal IUD use increased breast cancer risk by 40 percent, or 14 extra women diagnosed with breast cancer per 10,000 users of hormonal IUDs compared to nonusers.
The study shows an increasing trend associated with prolonged IUD use; however, these findings were not statistically significant.
Dividing the data by duration reduced the statistical precision, yet the upward trend indicates potential increased risk over time, Morch said, noting that this trend has been observed in other studies as well. Further research is necessary to solidify these observations.
“The theory behind this is that many forms of breast cancer are hormonally-based,” Dr. Daniel Landau, oncologist, hematologist, and contributor for The Mesothelioma Center at Asbestos.com, told The Epoch Times via email.
“Estrogen (or sometimes progesterone) actually ‘feeds’ breast cancer,” he wrote. “These cancers are called hormone receptor positive breast cancers.”
Morch highlighted that the increase in breast cancer risk observed in the study is primarily attributed to the prevalent use of a high-dose hormonal IUD, Mirena, among Danish women in recent years. Most of the IUDs examined were high-dose, she said, noting that this context is vital for interpreting the results.
Mirena is one of four hormonal IUDs approved in the United States.
Distinctions Between Types of Contraceptives
Hormonal IUDs release a synthetic hormone that thickens cervical mucus to block sperm movement, thinning the uterine lining to make it less hospitable for a fertilized egg to implant. It may also prevent ovulation.All hormone contraceptives contain synthetic forms of either progesterone alone or both estrogen and progesterone, which are naturally produced in a woman’s ovaries. It was previously believed that these hormones functioned solely within the reproductive system, yet recent findings suggest that they have broader systemic effects.
Conversely, copper IUDs are hormone-free, and use copper to create a toxic environment for sperm, impeding its movement toward an egg.
IUDs fall under long-acting reversible contraception, along with implants, which are small, flexible rods inserted under the skin of the upper arm.
“Medicinal contraceptives carry cardiovascular risks, including blood clots. The risk of blood clots occurs particularly with estrogen-containing methods, especially in smokers or those over 35,” Dr. Lauren Ramsey, a breast cancer surgeon from Fort Worth, Texas, who was not part of the study, told The Epoch Times.
Blood Clots Versus Breast Cancer
The results of the study showed that the breast cancer risk of short-term IUD use was comparable to that of contraceptive pills.Guidelines for birth control pill use have been updated in the past as a result of research that has linked certain pills to an increased risk of blood clots.
“These birth control pill recommendations were made based on a blood clot risk similar to the risk we now show for breast cancer,” Morch said.
Therefore, it is crucial to view the breast cancer risk we have observed as significant, she said.
Weighing Risks and Benefits of Contraceptives
The decision to use contraception involves a careful evaluation of both risks and benefits.While some birth control pills may increase the risk of cervical and breast cancer, they also lower the risk of excessive cell growth associated with endometrial cancer. All birth control pills inhibit ovulation, and some can also stop pregnancies.
Potential side effects of contraceptives include missed menstrual cycles, nausea, mood swings, and breast tenderness.
Know the Risks
Contraceptives should be approached as medications, according to Landau, which inherently come with risks. Women deciding to use hormonal contraception should be fully informed about its associated hazards, such as an elevated risk of blood clotting and breast cancer.- Short-acting hormonal methods, such as injectables and progestin-only pills. Progestin-containing pills thin the uterus lining and prevent fertilized eggs from implantation.
- Combined hormonal methods, which contain synthetic estrogen and a type of progestin, such as combined oral contraceptives, also known as “the pill,” contraceptive patches, and vaginal rings. All combined hormonal methods can prevent fertilized eggs from implantation.
- Emergency contraception, which is used post-intercourse and includes emergency contraceptive pills. Emergency contraceptives do not prevent implantation but prevent ovulation.
- Copper IUDs
- Barrier methods, such as devices preventing sperm from penetrating the uterus, such as condoms and diaphragms
- Sterilization, which includes tubal ligation, vasectomy, and implants
However, she urged women in their 30s and 40s to remain informed about this association when discussing contraceptive options with their health care providers.
“If you have a family history of breast cancer or are especially concerned about the risk of developing breast cancer, perhaps discuss non-hormonal birth control options,” Landau wrote.
Ramsey said, “Balancing the benefits and risks of contraceptive methods requires a comprehensive approach. It’s an individualized decision that takes into account personal and family medical history.”
The takeaway from this new study is that contrary to the previous belief that hormonal contraceptives are risk-free, they are medications with systemic effects, according to Morch. This perspective should guide women as they weigh their reasons for initiating contraceptive methods against the risks involved.
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